1. Field of the Invention
The present invention is related to a pixel array of an image sensor and a method of fabricating the same, and more particularly, to a pixel array of an image sensor with intermixing color-sensing and a method of fabricating the same
2. Description of the Prior Art
Light is the portion of electromagnetic radiation whose wavelength is between 300 nm (ultraviolet) to 14,000 nm (far infrared). The optical spectrum of visible light lies in a wavelength range from about 380 to about 780 nm. An image sensor configured to convert optical signals into electrical signals is widely used in digital cameras, cellular phones, surveillance, medical, automobile, and other applications. The pixel array of an image sensor normally includes color pixels such as red, green and blue pixels. Panchromatic pixels, also known as clear pixels or white pixels, may also be adopted for improving the sensitivity of the image sensor.
FIG. 1 is a diagram illustrating the cross-sectional view of a pixel array 10 in a conventional image sensor during different manufacturing stages. For illustrative purpose, only one red pixel R, one green pixel G, one blue pixel B and one panchromatic pixel P are depicted. At stage S1, the red pixel R, the green pixel G, the blue pixel B and the panchromatic pixel P are formed on a substrate 12. At stage S2, planarization material is deposited on the red pixel R, the green pixel G, the blue pixel B and the panchromatic pixel P to form the planarization layer 14. At stage S3, micro-lenses LR, LG, LB and LP are formed on the planarization layer 14 at locations corresponding to the red pixel R, the green pixel G, the blue pixel B and the panchromatic pixel P, respectively.
In the conventional pixel array 10, the color pixels R, G, B and the panchromatic pixel P are fabricated in difference processes. More specifically, at least one photo mask is required to define the pattern of the color pixels, and another photo mask is required to define the pattern of the panchromatic pixels. Although the panchromatic pixels can improve the sensitivity, they require using extra photo masks in an extra step, thereby increasing the complexity and cost of the manufacturing process.